Scientists and hardcore geotagging photo enthusiasts have been doing this for years, but it's been hard, slow and expensive. The most common approach is the use of special hardware that "logs" where a GPS device is at every moment. Later, software matches the exact time a photo was taken with the location of the GPS device at that same moment as seen in the log, and voila, the picture can be geotagged. But that process is obviously not easy enough to be useful to the general public.

Geotagging isn't just for experts. Consumers do it, too. Flickr added geotagging in August. It works by showing you a satellite view or map of any place on Earth, plus thumbnails of your uploaded photos. By dragging and dropping each thumbnail onto the location on the map where it was taken, Flickr geocodes it.

You can also use Trippermap Geotagger to employ the powerful Google Earth in a way that supports Flickr geotagging.

A product called the Jelbert GeoTagger attaches to a digital camera's flash shoe. When you take a picture, the GeoTagger captures the location via GPS -- even the direction the lens is pointed using an internal compass. Later, you can use third-party software to merge all that data with the picture files themselves. It requires that you buy a Geko 301 GPS receiver from Garmin.

Dozens of camera phones already sport built-in GPS, including the Nokia N95, RIM BlackBerry 8800 and the HTC P3600 Windows Mobile smart phone.